Siemens SAB 80515 Series User Manual page 67

Figure 7-20
Special Function Register TMOD (Address 89 H )
89 H GATE
Timer/counter 0/1 mode control register.
Bit
Gate
C/T
M1 M0
0 0
0 1
1 0
1 1
1 1
Semiconductor Group
C/T M1 M0
Timer 1
Symbol
Gating control.
When set, timer/counter "x" is enabled only while "INTx" pin is high and
"TRx" control bit is set.
When cleared timer "x" is enabled whenever "TRx" control bit is set.
Counter or timer select bit.
Set for counter operation (input from "Tx" input pin).
Cleared for timer operation (input from internal system clock).
8-bit timer/counter
"THx" operates as 8-bit timer/counter
"TLx" serves as 5-bit prescaler.
16-bit timer/counter.
"THx" and "TLx" are cascaded; there is no prescaler.
8-bit auto-reload timer/counter.
"THx" holds a value which is to be reloaded into "TLx" each time it
overflows.
Timer 0:
TL0 is an 8-bit timer/counter controlled by the standard timer 0 control
bits. TH00 is an 8-bit timer only controlled by timer 1 control bits.
Timer 1:
Timer/counter 1 stops
On-Chip Peripheral Components
GATE C/T
Timer 0
*
67
M1 M0 TMOD